#include "common.h"

int peakIndexInMountainArray(vector<int>& arr)
{
	int left = 0;
	int right = arr.size() - 1;
	while (left <= right)
	{
		int mid = left + (right - left) / 2;
		if (arr[mid] < arr[mid + 1]) left = mid + 1;
		else if (arr[mid] < arr[mid - 1]) right = mid - 1;
		else return mid;
	}
	return 0;
}